U.S. patent number 5,199,239 [Application Number 07/767,581] was granted by the patent office on 1993-04-06 for housing seal interface.
This patent grant is currently assigned to Honeywell Inc.. Invention is credited to Edgar W. Younger.
United States Patent |
5,199,239 |
Younger |
April 6, 1993 |
Housing seal interface
Abstract
The joint between two nearly rigid, mating walls has a tongue on
one wall's surface and a groove on the other wall's surface which
have special cross section shapes cooperating to resist penetration
of the joint by fluids such as water. At least one of the walls is
formed of a plastic material which deforms under compressive
loading. The shape of the tongue includes sides thereof which
intersect the end to form corners defining the longitudinal edges
of the tongue. The groove has walls which converge toward each
other at the bottom of the groove from a mouth wider than the width
of the end of the tongue. The shape of the groove forms a line of
contact with each of the tongue's corners when the tongue is mated
with the groove. During assembly, the corners of the tongue are
forced into the walls of the groove by some type of clamping
mechanism so as to at least slightly deform at least one of the
tongue and groove.
Inventors: |
Younger; Edgar W. (Plymouth,
MN) |
Assignee: |
Honeywell Inc. (Minneapolis,
MN)
|
Family
ID: |
25079916 |
Appl.
No.: |
07/767,581 |
Filed: |
September 30, 1991 |
Current U.S.
Class: |
52/592.5;
174/481; 220/327; 220/4.21; 403/274; 52/233 |
Current CPC
Class: |
B29C
66/1142 (20130101); F16J 15/04 (20130101); H02B
1/28 (20130101); H05K 5/063 (20130101); B29C
65/562 (20130101); B29C 66/54 (20130101); H02B
1/46 (20130101); Y10T 403/49 (20150115) |
Current International
Class: |
B29C
65/00 (20060101); F16J 15/02 (20060101); F16J
15/04 (20060101); H02B 1/28 (20060101); H02B
1/00 (20060101); H05K 5/06 (20060101); H02B
1/46 (20060101); B65D 043/04 () |
Field of
Search: |
;52/595,584,233
;403/274,284,312 ;174/49 ;220/4.21,4.24,327 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Scherbel; David A.
Assistant Examiner: Wood; Wynn E.
Attorney, Agent or Firm: Schwarz; Edward
Claims
What I claim is:
1. An interface assembly for sealing, abutting surfaces of first
and second walls, against penetration by fluids at least one wall
is comprised of nearly rigid material which deforms under load,
comprising in the first wall and extending along at least a portion
of the abutting surface a groove having an opening of predetermined
width and an interior surface having opposing walls converging
toward the bottom thereof, and along the second wall's abutting
surface a tongue having a base, sides projecting from the base, and
an end surface spaced from the base and intersecting both sides,
the intersection of said end surface and said sides defining
corners spaced from each other by a predetermined amount less than
the predetermined width of the groove's mouth, said tongue and
groove having relative dimensions and shapes allowing the tongue to
enter the groove and mate with non-surface contact therewith, with
each corner of the tongue forming a line of contact with one of the
groove's walls, and clamping means in mechanical connection with
the walls for forcing the tongue's corners against the groove's
sides and for causing deformation of at least one of the tongue and
the groove along the lines of contact between the tongue's corners
and the groove's walls.
2. The assembly of claim 1, wherein the sides and end of the tongue
are each substantially flat surfaces.
3. The assembly of claim 2, wherein the clamping means comprises a
projection on each of the first and second walls in alignment with
each other and in each projection a cylindrical bore coaxial with
the cylindrical bore in the other projection, and a cylindrical
fastener in the two cylindrical bores for drawing the two walls
toward each other.
4. The assembly of claim 3, wherein the projections are integral
with their respective walls.
5. The assembly of claim 2, wherein the corners formed by the
intersections of the sides and end of the tongue have a radius of
curvature not greater than about 0.25 mm.
6. The assembly of claim 5, wherein the walls are formed of
mineral-filled thermoplastic.
7. The assembly of claim 1 wherein the base of the groove between
the lines of contact of the groove with the tongue has a radius of
curvature substantially smaller than that of the end of the
tongue.
8. The assembly of claim 1, wherein the cross section of each of
the tongue and the groove is uniform along the length of the tongue
and the groove.
9. The assembly of claim 8, wherein the cross section of each of
the tongue and the groove is bilaterally symmetric.
10. The assembly of claim 1, wherein the cross section of the
groove is circular in the vicinity of the lines of contact with the
tongue.
11. The assembly of claim 10, wherein the dimensions of the tongue
and groove cooperatively cause a clearance space to be formed
between them when the tongue mates with the groove.
12. The assembly of claim 1, wherein the dimensions of the tongue
and groove cooperatively cause a clearance space to be formed
between them when the tongue mates with the groove.
Description
BACKGROUND OF THE INVENTION
It is frequently desirable to seal the joint between two walls or
surfaces of an enclosure so as to prevent or resist penetration of
the joint by fluids such as water. There are different types of
exposure to fluids. In certain situations, the joint immersed in
the fluid and there is positive pressure forcing the fluid against
the joint to breach it. In other circumstances, the fluid is a
liquid which merely wets the exterior of the walls involved and
there is no positive pressure forcing the liquid into the joint. In
this latter case, the presence of the liquid may result from
condensation or rain.
This need to seal a joint to prevent its penetration by some fluid
arises very frequently in the packaging of electronic equipment for
use in a damp or wet environment for example. The problem has of
course been solved successfully by the use of O-ring gaskets such
as found in water resistant watch cases. It is also well known to
use liquid caulks and sealants or flat gaskets to form this seal.
But one can see that each of these solutions requires an additional
element or material in order to effect the seal. This increases the
cost and complexity of the assembly process. In addition, since the
seal is formed within the joint itself, improper seating of the
gasket can occur on occasion without any way available to detect
this condition.
BRIEF DESCRIPTION OF THE INVENTION
An adequate interface for sealing abutting surfaces of first and
second nearly rigid walls, at least one comprised of material which
plastically deforms under load, comprises in the first wall and
extending along at least a portion of the abutting surface a groove
having an opening of predetermined width. The groove has an
interior surface having opposing walls converging toward the bottom
thereof. Along the second wall's abutting surface there extends a
tongue having a base, sides projecting from the base, and an end
surface spaced from the base and intersecting both sides. The
intersection of this end surface and sides defines corners parallel
to each other and spaced from each other by a predetermined amount
less than the predetermined width of the groove's mouth. The tongue
and groove have relative dimensions and shapes allowing the tongue
to enter the groove and mate therewith, with each corner of the
tongue forming a line of contact with one of the groove's walls.
Clamping means in mechanical connection with the walls force the
tongue's corners against the groove's sides and cause deformation
of at least one of the tongue and the groove along the lines of
contact between the tongue's corners and the groove's walls.
This structure resists penetration by liquids in all situations
except where the walls are actually immersed in the liquid.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an enclosure having walls which
carry the invention on the edges thereof.
FIG. 2 is a cross section of first and second walls adjacent to the
abutting surfaces thereof when unmated.
FIG. 3 is a cross section of first and second walls adjacent to the
abutting surfaces thereof when mated.
FIG. 4 is a blow-up of the cross section of first and second walls
when mated and adjacent to a line of contact thereof between the
tongue and the groove.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turn first to FIG. 1, which shows a simple rectangular box
employing the invention and suitable for enclosing electronic
circuitry or other apparatus which must be protected from fluids
such as water. In this embodiment, the box has a top half 12 and a
bottom half 11, each comprising a pair of mating walls 18 and 17
respectively, as well as other mating wall pairs and a top or
bottom which have not been designated with reference numbers. Each
wall 18 and 17 has respectively an abutting surface or surface 20
and 19. Each half 12 and 11 is formed from material which is
substantially rigid. However, at least one of each pair of mating
walls must be formed of material which is deformable under load.
This deformable material may be either plastically or elastically
deformable. One preferred type of material which is used for
forming the entire box halves 12 and 11 is a nylon-based
mineral-filled engineering plastic from which the box halves 12 and
11 may be formed by injection molding. Such material may be
purchased commercially from Dupont Corporation, Wilmington, Del.
under the trade name Minlon 10B.
Top and bottom halves 12 and 11 are held together by projections 14
and 13 respectively carried on walls 18 and 17 and integral
therewith, although any type of clamping means may be used to force
the abutting surface 20 of wall 18 against the corresponding
abutting surface 19 of wall 17. Projections 14 and 13 have
cylindrical bores therein which are coaxial with each other. Screw
type fasteners 15 pass through the bores in projections 14 and
engage the walls of the bores in the projections 13 to clamp box
half 12 against box half 11, forcing surface 20 toward edge 19.
Turn next to FIGS. 2 and 3 where details of the abutting surfaces
20 and 19 are shown cross sectionally. The edge 20 includes a
tongue 22 extending along the entire length of edge 20 as well as
along the edges of the other walls of box half 12. The tongue 22 is
defined by sides 28 and 29 shown in edge view in FIGS. 2 and 3 and
projecting from a base portion 34 of abutting surface 20. An end 21
intersects the sides 28 and 29 and forms at these intersections,
corners 36 and 37 which extend along the entire length of tongue
22. In the typical design, the cross section of tongue 22 and the
adjacent abutting surface 20 is uniform along the entire length of
tongue 22, so that sides 28 and 29 are parallel to each other.
Corners 36 and 37 are not sharp, but have a radius of curvature of
a few thousands of an inch, and in my preferred design, 0.010 in.
(0.25 mm.). This is easy to achieve by standard injection molding
techniques. Sides 28 and 29 are each inclined to a vertical
centerline of FIG. 2 or 3 by a few degrees, and the preferred
design has this angle at 10.degree.. The width of end 21 in my
preferred design is 0.031 in. (0.78 mm) and the total length of
tongue 22 from end 21 to edge 20 is 0.06 in. (1.5 mm.).
The bottom half's abutting surface 19 includes a groove 27
extending the entire length of wall 17. Groove 27 is defined by
opposing walls 23 and 25 which converge toward the bottom 24 of the
groove 27. In a preferred embodiment, the cross section of groove
27 in the vicinity of the contact points of is circular, although
other profile shapes are probably suitable. The width of groove 27
at edge 19 must be greater than the width of the tongue's end 21.
The depth of groove 27 where its width equals that of the width of
the tongue's end 21 must be less than the cross-sectional length of
tongue 22 as it projects from wall 18. That is, there must be a
clearance space between surfaces 19 and 20 when tongue 22 is in
interference contact with groove 27. It is likely that a much wider
range of angles will prove satisfactory for the inclination from
the centerline of sides 28 and 29, than the 10.degree. mentioned
above.
The seal is formed by mating tongue 22 into groove 27 and applying
sufficient force symbolized in FIG. 3 as the arrows labeled F, to
cause some deformation of at least on of the tongue 22 and the
groove 27. For the engineering plastic identified as suitable
material from which to make the walls 17 and 18, screws 15 may be
spaced from 3 to 3.5 in. (7.6 to 8.9 cm.) and torqued to 11 to 12
in. lb. (12.7 to 13.9 cm. kg.) to provide adequate joining
force.
FIG. 4 shows in an idealized way how a corner of tongue 22 may
distort under adequate joining force. Line 41 is tangent to the
sides of groove 27 at the depth where the width of groove 27 equals
the width of the tongue's end 21 and thus where the corners of
tongue 22 contact the walls of groove 27. Line 41 makes an angle
with the groove centerline 40 of around 55.degree. to 60.degree. in
a preferred embodiment.
One can thus see that a seal between walls formed from nearly rigid
materials according to this invention is strongly resistant to
penetration by liquids, and is thus suitable for housing electronic
equipment and other devices in environments subjected to damaging
liquid sprays.
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